Body fat mass is known as one index used for determining the health of a measurement subject. In particular, a visceral fat mass is known as an index used for determining whether or not a measurement subject suffers from central obesity. Central obesity is said to bring about lifestyle-related diseases that can easily lead to artery hardening, such as diabetes, hypertension, and hyperlipidemia. The aforementioned indexes hold promise in terms of preventing such diseases.
“Visceral fat” refers to fat that builds up in the periphery of the internal organs, and is located on the inner sides of the abdominal muscles and back muscles. Visceral fat is distinguished from subcutaneous fat, which is located in the surface layers of the trunk area. It is typical to employ the area occupied by visceral fat in a cross-section of the trunk area that corresponds to the navel (referred to as a “visceral fat cross-sectional area” hereinafter) as an indicator of the visceral fat mass.
Normally, visceral fat mass is measured by analyzing images obtained through X-ray computed tomography (CT), magnetic resonance imaging (MRI), or the like. In this image analysis, a tomographic image of the trunk area is obtained through the X-ray CT or the like, and the visceral fat cross-sectional area is calculated geometrically from the cross-sectional image.
X-ray CT machines are installed in most medical facilities, and it is difficult to measure a visceral fat mass on a daily basis using the stated image analysis technique. Furthermore, because X-ray CT and the like obtain tomographic images using radiation, it is undesirable to measure the visceral fat mass on a daily basis using X-ray CT and the like.
A body impedance technique is being considered as a method for measuring a body fat mass, as an alternative to image analysis using X-ray CT or the like. In the body impedance technique, electrodes are placed in contact with the four limbs, and a body impedance is measured using those electrodes. The body fat mass is then calculated based on the body impedance.
A body fat measurement device that uses the body impedance technique makes it possible to accurately measure the extent of body fat buildup throughout the entire body or in specific areas such as the four limbs, the trunk area, or the like. However, conventional body fat measurement devices that use the body impedance technique affix electrodes only to the four limbs, as mentioned above. Conventional body fat measurement devices that use the body impedance technique thus cannot make accurate measurements by extracting the extent of visceral fat building, the extent of subcutaneous fat buildup, and so on.
JP 2002-369806A (Patent Literature 1) discloses a technique related to a body fat measurement device. In this body fat measurement device, electrodes are provided on the inner circumferential surface of a belt member. The belt member is affixed to a measurement subject's trunk area, and thus the electrodes are placed in contact with the trunk area.
Meanwhile, JP 2007-014664A (Patent Literature 2) discloses a technique related to a body fat measurement device. In this body fat measurement device, a fitting unit that is fitted onto a measurement subject's trunk area and a lower limb unit onto which the measurement subject steps are configured as separate units. Abdominal area electrodes and handle portions are provided in the fitting unit, and hand electrodes are provided in the handle portions. Foot electrodes are provided in the lower limb unit. By gripping the handle portions with his/her hands, the measurement subject brings the hand electrodes into contact with his/her palms. Then, by pressing the fitting unit against his/her abdominal area using his/her hands that grip the handles, the measurement subject brings the abdominal area electrodes into contact with his/her abdominal area. The measurement subject then brings the foot electrodes into contact with the soles of his/her feet by stepping onto the lower limb unit.